Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 211	$ 346	$ 761	$ 2,621
Other comprehensive income (loss), net of tax:
Net gains (losses) on available-for-sale securities	(2)	(1)	6	2
Net gains (losses) on derivative instruments	(26)	(29)	(106)	(4)
Foreign currency translation adjustments	23	7	56	(1)
Total other comprehensive income (loss), net of tax	(5)	(23)	(44)	(3)
Total comprehensive income (loss)	$ 206	$ 323	$ 717	$ 2,618